The cyclic carbonate monomers have unique properties. For example, they can be simply synthesized into products with high yield and high purity; and they can be initiated through small molecules or macromolecules to obtain bio-degradable polycarbonate. The polymers of the cyclic carbonate monomers have outstanding performance. For example, they generally have favorable biocompatibility, and can be degraded in vivo; the degradation products can be absorbed in human body, or be excreted through normal physiological pathways. Similar with the aliphatic polyesters, they are widely used in various areas of biomedicine, e.g. surgical sutures, orthopedic fixation devices, scaffold materials for biological tissue engineering, carriers for controlled drug release, etc. Among these, the synthetic bio-degradable polymers received much attention, since they have low immunogenicity, and their performances like degradation performance and mechanical performance can be conveniently controlled. The commonly used bio-degradable polymers are obtained through ring-opening polymerization of cyclic carbonate monomers like cyclic trimethylene carbonate (TMC), or cyclic ester monomers like glycolide (GA), lactide (LA), caprolactone (CL), etc. The bio-degradable polymers have been approved by the U.S. Food and Drug Administration (FDA).